Anchor Dragging Story (long)

[Nomad Willy]

Ghost,
Even ghosts appear at times. Good.
Unknowns and more variables keep coming up.
How much was the bow bobbing up and down?
Was the boat sailing badly w/o a bridal?
Was the boat windage excessive? Sounds like the boat was a sundeck and frequently they are very high up and with oxygen tent. And in the southern waters frequently these boats are cover w kayaks and other fun in the sun toys. Windage could have been huge. And speaking of windage it was called out by the OP as a gale. There's a big difference between a little gale and a big gale.
Plug in a few variables on the negative side and the 45lb anchor would definitely be too small.
SoWhat wrote;
"Sometimes you get the bear, sometimes the bear gets you."
Didn't think much about it at first but perhaps SoWhat was talking about these variables. I hope he was because it certainly does.
Yup there are times when the anchor is too small.

Ghost I lay down the rode about the same way.

 

[sunchaser]

Ghost,
Unknowns and more variables keep coming up.
How much was the bow bobbing up and down?
Was the boat sailing badly w/o a bridal?
Was the boat windage excessive? Sounds like the boat was a sundeck and frequently they are very high up and with oxygen tent. And in the southern waters frequently these boats are cover w kayaks and other fun in the sun toys. Windage could have been huge. And speaking of windage it was called out by the OP as a gale. There's a big difference between a little gale and a big gale.
Plug in a few variables on the negative side and the 45lb anchor would definitely be too small.
.

Good points Eric. In our case where deeper sets, large tidal ranges and smaller anchorages are not uncommon, there is no way we can lay down much more than a 4:1 high tide scope. For this reason alone I prefer a size or two up the anchor chart. In predicted big blows we detour for safe, shallow (less than 50 high tide feet) and good holding harbors.

 

[Montenido]

Hi everybody,

Thank you all for the good points and arguments brought up. To answer a few questions, it was a sand bottom with no weeds. I've anchored here dozens of times with no problems. I did (and do) back up while paying out chain, so I know it was not piled on the anchor. I was not using the slot in the shank, so the chain should not have pulled on the anchor in the wrong way. The bay I was in is very flat-bottomed, so even though I was in 10-12' of water, I had a good distance between me and the beach.

When I anchored that afternoon, there were stiff breezes coming from the south, but my spot was calm and sheltered. By the time I woke up with all hell breaking loose, the bow had been bobbing up and down with the wind waves for a while. One disadvantage of an aft stateroom is that I can't really feel that motion, which is great when sleeping normally.

I will be bringing a larger anchor than the replacement 55# Rocna that I currently have next time I drive down. Bigger is always better in my book. I will also start putting out a bit more rode, 8-10:1 in the future. I plan to start using an anchor alarm as part of my daily routine. I agree with all who said that we were lucky to get out with no injuries, damage or loss. In this part of Mexico, if you go ashore in a hard grounding that damages your running gear, your boat is basically gone. There is no vessel assist or anything like that to bail you out or tow you into port. If you leave your vessel unoccupied to seek help, it will probably be stripped while you are gone.

This was a very scary lesson for me, and I hope it reminds all of you to take care when anchoring.

Be careful out there. Cheers. Bill

 

[Ski in NC]

I've been in similar situations, once on my boat, once as crew on another. Once in the Keys where bottom was eel snot on top of cap rock, the other we think was a layer of sand on top of cap rock in the Bahamas.

Hearing the wind pick up in the middle of night is a crappy feeling. Worse then to get up and see the surf breaking 50' behind the transom (Bahamas incident). Wake up crew, fire up engines, feather gears to get some fwd thrust without allowing boat to turn. Crew pulls anchor, creep boat fwd with gears, go upwind and drop it again. Check holding. Stay up all night monitoring conditions. Crew goes back to sleep. Next day pretty exhausted.

Better that than getting woke up by boat hitting the beach!!!

 

[Nomad Willy]

Bill,
Thanks for the filling us in.
The Rocna may be enough if you never use schort scope. Almost nothing beats it other than short scope.
And I have read numerous very high wind stories in Baha. On a boat like mine just a bridal could increase my holding power a lot. And I don't have one. One of the few IMO short commings of mostly line rode.

Not going to recommend a replacement brand anchor for fear of high velocity thrown tomatoes .. or worse. But I will say I don't think your anchor brand had anything to do w your drag. Well I just thought of something else. The Fortress does have a grand reputation holding in sand .. or anything else .. if the bottom is suitable.

 

[dhays]

Here is a question I missed. Bill, you mentioned you had 20' snubbers. Can you describe what you had? Was this in the form of a bridle, a single line snubber, and what type of line was used for the snubber?

FWIW, I use a bridle made up of 1/2" nylon three-strand.

 

[MurrayM]

Has anybody asked what height your bow is off the water, and did you add that to the water depth?

 

[hjorgan]

It's a sick feeling. We had rented a houseboat in the Keys. 2 anchors out, one a huge danforth and the other a plow type. Neither was holding and it was blowing 40 knots. Had to get on the engine and keep her off the mangroves for 6 hours. Problem was grass and mud. Nothing to hold and not enough rode or chain to help set. That's the last houseboat trip for me.

 

[Peter B]

Hi everybody,

Thank you all for the good points and arguments brought up. To answer a few questions, it was a sand bottom with no weeds. I've anchored here dozens of times with no problems. I did (and do) back up while paying out chain, so I know it was not piled on the anchor. I was not using the slot in the shank, so the chain should not have pulled on the anchor in the wrong way. The bay I was in is very flat-bottomed, so even though I was in 10-12' of water, I had a good distance between me and the beach.

This was a very scary lesson for me, and I hope it reminds all of you to take care when anchoring.

Be careful out there. Cheers. Bill

Bill, having read right through, I think you did all the right things and were just unlucky that the bottom being sand, just did not provide quite enough hold for the conditions. I suspect if the winds and waves had just been a mite less, you would have been fine - just bad luck really.

In my view your scope should have been fine. Evidence is that more than the 1 : 7 you had out, being all chain, should have been plenty, and more would probably have made no difference.
Going to a bigger anchor might well help in similar situation, but more than the extra weight, I think extra fluke area might be more relevant - which of course you do get with a bigger anchor as a rule anyway. However, this aspect is what does give the spade types a bit of an edge over some, as they bury deeper and have a larger fluke area for their given weight.

 

[Nomad Willy]

Fluke area is good Peter.

But for a given size anchor of steel any increase in fluke area will basically require other appendages and parts to be smaller and or lighter. So anchors w heavy non fluke parts will have relativly smakk flukes.

 

[foggysail]

Bill-- read your horrors, been there done that! No need for me to go though all the details other than to mention that I had no luck with a 55 along with an 88# Delta with my Silverton 40. THEY PLOWED!

Now I have an 80# Manson Supreme that I wrote about in the anchor section of the forums. THAT DOG ALSO FAILED! My situation happened during an afternoon (THANK GOD!) rather than the usual failure time between 1-3AM. I was anchored in 8-10' of water with a scope of about 6 going on memory. Had been on anchor for about 2 days when we had a wind shift of 180 degrees. Oh-- my rode is 5/16" HT chain.

Now maybe the anchor would have reset but in a crowded harbor, one just cannot screw around so I caught the slip and reset the anchor under power. I believe the anchor was chuck full of bottom mud which prevented it from resetting on its own.

Those who followed my adventure as posted gave me the usual "Hey--- a Manson Supreme doesn't slip! Are you sure you set it properly?" Or words to that affect. Well, I WILL tell you, the #$%&^* things WILL slip!!!!! I have come to the conclusion that there is NO right anchor!!!

Now someone mentioned that the makers of the Manson recommends a scope of 10 in stormy weather. I have no clue where the guy at Manson anchors, we do not live or boat in the conditions of yesterday when all boats were made of either metal or wood. HARBORS ARE CROWDED!!!!

So while out there with my pants spoiled after re-anchoring, I got out my trusty laptop and ordered a big aluminum Fortress which still sits in the original box. I forgot which one I purchased other than it was about $700 from Defender and I think it weighs 35 pounds or so. I WILL SET THAT ANCHOR UP for the coming season. I cannot easily use my huge windlass with it but at least I should be able to struggle manually if I need to use it.

SOOoooo..... good luck with your newer anchor! If I had my purchase to do over, I would have purchased something that weighs over 100#! Yeah, not to pick on others but when the chips are down, it matters not that others claimed "gee, your Manson should have held, are you sure you.....!" I have been anchoring now for 30+ years and believe the bigger the boat, the greater the anchoring challenge.

Foggy

EDIT: My Fortress is an FX55, weighs 32# and currently is going for $795 on EBay where I remember I purchasing it.

 

[Peter B]

Fluke area is good Peter.

But for a given size anchor of steel any increase in fluke area will basically require other appendages and parts to be smaller and or lighter. So anchors w heavy non fluke parts will have relativly small flukes.

Point taken Eric, which is why I implied that larger fluke area be preferred over 'just bigger', because with just going bigger, one gets much more weight added for a quite modest increase in fluke area.

Also, I really think this is possibly another example, when added to foggysail's story, of the disadvantage of the concave, or as you describe them, scooped fluke shape. They tend to hold the substrate on the fluke if at all 'sticky', and that will prevent re-setting on a tide or wind change if the fluke remains clogged.

This is why Rex Francis, of Anchor Right, after much research, went back to the convex fluke shape with the Sarcas, as it sheds the bottom stuff so much better, so that that vital re-set is not impaired, and leaving you dragging at 0 dark thirty on some nasty night.

Steve of Panope's anchor setting videos showed this aspect of their behaviour very clearly. This explains why the convex fluke types may have a bit less absolute holding in one sustained drag test, but if they move, they literally plow along still under the substrate, often going even deeper rather than get so full of substrate they pop out suddenly, like must have happened to the OP. They then often take firm hold again, with little distance lost, especially if a direction change mandates a quick re-set.

 

[Nomad Willy]

Yup all roll bar anchors have that problem ... if it's a problem. Except your SARCA because it has a large dia skinny roll bar. Could be a problem but I've never met anybody with it.

 

[grahamdouglass]

For informative reading at bedtime in anchorages, nothing is better than Hinz on anchoring.
https://www.amazon.ca/Complete-Book-Anchoring-Mooring/dp/0870335391.

Over 300 pages on how to anchor a boat. I found it an enjoyable read.

 

[Peter B]

Yup all roll bar anchors have that problem ... if it's a problem. Except your SARCA because it has a large dia skinny roll bar. Could be a problem but I've never met anybody with it.

No Eric, with all due respect, all roll bar anchors don't have that problem. That is your assumption, not supported by any of the evidence in Steve's videos. It is the scooped fluke filling up, not the roll bar, that causes the problem. But yes, I also agree the roll bars on the Supreme (which you cut off) and the Rocna, are too thick for my liking - and thicker than they need to be.

 

[BruceK]

If you are having anchor issues you should at least view Steve(SV Panope)`s tests, on TF. Decide for yourself whether the 3 or so anchors which did well in the initial set, reversal reset, and scope shortening tests, are of any interest to you.
I`m sure there are old design anchors which have performed well and earned their place on your boat, but as with anything, there can be improvements. It is everyone`s prerogative to dismiss the newer well rated anchors, but at least take a look. If anything can help prevent ending up dragging towards a beach at night in foul conditions it has to be worth considering.

 

[Marlinmike]

This post was very interesting, thanks to the original OP for an honest detail into his situation. Having a fly-bridge boat and sleeping in the forward cabin, what anchor alarms does everyone use, or at least in my situation, can't hear the bridge GPS and my phone won't be able to "see" satellites below in cabin...?

 

[Yahoo 1]

This post was very interesting, thanks to the original OP for an honest detail into his situation. Having a fly-bridge boat and sleeping in the forward cabin, what anchor alarms does everyone use, or at least in my situation, can't hear the bridge GPS and my phone won't be able to "see" satellites below in cabin...?

After several tests with many, I use Anchor Watch

 

[Nomad Willy]

Peter,

Sorry such a long thread but this needs to be put to rest.

Concave flukes (scoop) flukes tend to keep the substrate on the fluke where it will do the most good. Convex flukes (plow) tends to shed the substrate where it is lost, not retained on the fluke and lost to the benefit of holding power.

The Frenchman that designed the Spade did a lot of research into what shape was best for maximum resistance. An anemometer wouldn’t work if this was not how fluids move over a surface. Convex = less drag Concave = more drag. Many things are shaped the way they are because of this function.

So concave lifts the seafloor up and convex cleaves it off to the side.

But there are degrees of convexness and concaveness (or even flat) and (important to us) other surfaces attached to a fluke will act on the the whole structure we call an anchor. Stocks, shanks, pads (like on a Danforth), shackles, roll bars, ect ect. So by the time all the resulting forces are tallied up there is much more to consider than just maximum resistance of the fluke.

And an anchor has many other jobs to do other than provide max resistance. It must orientate the fluke to a position to penetrate the seafloor and hold it in the optimal attitude or the anchor may have substandard performance .. or not work at all.

The concave fluke compresses the substrate as it passes over the fluke by its up ended edges. The substrate finds it difficult to fall off the fluke. Then more substrate piles op on the fluke helping hold the anchor down. More holding power. But when you pull the anchor up sometimes (or frequently depending on where you anchor) there will be a big heavy ball of mud stuck fairly well to the fluke. PITA.

The convex fluke sheds the substrate a bit like rain on a roof. The substrate readily tends to sluff off the fluke, to the side of the anchor doing little to hold it down.

Most roll bar anchors have a “fat” roll bar of only moderate OD that presents a relatively small hole for the substrate to pass through. It’s more or less jammed through the hole (the space between the RB and the fluke) and IMO to a small degree aids resistance of the anchor. This is one of the reasons RB anchors tend to perform well .. holding power wise.
But the compaction is amplified by the RB, the up turned fluke and the presence of the shank right in the middle of the space at hand.

The RB on the SARCA is large in dia and w a skinny pipe (or rod) so the hole the substrate must pass through offers little resistance. The convex fluke offer less resistance as well so holding power is less. But the overall shape of the anchor promotes the anchor to sit upright much of the time while setting and it’s setting performance is excellent (or better). Also the same shape results in the anchor maintaining its attitude (basically sitting right side up) and the result is very excellent veering performance. Many RB anchors (and others) need to roll out (or nearly so) of the seafloor and reset. Not so the SARCA. Judging from Steve’s vids the SARCA just keeps pointing toward the boat .. perfect.

So Peter “all roll bar anchors don’t have that problem”
Agreed. The SARCA does not. And is a better anchor for it.
IMO the safest anchor possible is a SARCA one size up. I think that’s the way Rex recommends it.

 

[Montenido]

Okay,
A bit more info for my original story. I use two 1/2" 3-strand lines attached to my chain with rolling hitches as my snubber/bridle. I had about 20' on each side out. I believe that I might not have allowed enough for the 5-6' that my bow is above the water in calculating my rode length. So when the bow started hobby-horsing, my scope dropped to 5:1 or less. When I reset the same anchor, after clearing the beach, in deeper water with 150' of chain it set and held just fine.

I'm very grateful for all of the discussions that you all have added to this thread. Although I like to think that I know what I am doing, it is good to be reminded occasionally that I still have much to learn. I was very lucky that there were no boats downwind of me that I might have dragged into.

Stay safe everyone. Cheers, Bill

 

[BandB]

Did I miss it? I asked and never saw an answer as to why the OP was so opposed to the 55# Delta that came with the boat. At the very least, the previous owner had determined it to be appropriate.

 

[Nomad Willy]

BandB,
We've never had a discussion about the Delta that I recall. Seems to me it's an
OK anchor w/o any bad habbits or extreme pluses. Says on the anchor "fast set". Perhaps that is in reference to the lackluster setting reputation of the CQR. And it seems a direct decendant of the CQR. Not a rip off to be sure but more like a decendant.

Do you have one BandB?
Experience?
Must be plenty of other members w the Delta.
Any input may need a new thread though.

 

[dhays]

Okay,
A bit more info for my original story. I use two 1/2" 3-strand lines attached to my chain with rolling hitches as my snubber/bridle. I had about 20' on each side out.

I use the same system. Thanks.

 

[Nomad Willy]

Bill,
I see w your subsequent posts you did do a good job anchoring and kept you and yours safe. Many little bits of these discussions will come to the surface in the future and provide references to make new decisions .. better decisions.

Thanks for your anchoring input.

 

[MurrayM]

It seems to me that scope might have been an issue in your case. Manson recommends a minimum of 10:1 scope for 35 knot winds. Not knowing the height of your bow roller, I am guessing 5', giving you a vertical height of 17'. With 100' of chain out, you had a scope of under 6:1.


If there were any issues of bottom condition or poor set, that would only make the limited scope more of an issue. I think that the greater holding power at lower scope ratios of some of the current generation of anchors tends to give us false confidence in their abilities in heavier weather.


Then again, it never hurts to have a bigger anchor.

...I believe that I might not have allowed enough for the 5-6' that my bow is above the water in calculating my rode length. So when the bow started hobby-horsing, my scope dropped to 5:1 or less. When I reset the same anchor, after clearing the beach, in deeper water with 150' of chain it set and held just fine....

My guess is that's what the most important factor was, especially in shallow water where the extra distance to the bow (+ maybe the anchor was set at low tide + the bow would have been even higher on the wave crests) would have had a more dramatic effect on shortening scope than in deep water. To add even more of a problem, the hardest tugs on the anchor would have been on the wave crests, exactly when the scope was its least.

Thanks for posting this

 

[ranger58sb]

This post was very interesting, thanks to the original OP for an honest detail into his situation. Having a fly-bridge boat and sleeping in the forward cabin, what anchor alarms does everyone use, or at least in my situation, can't hear the bridge GPS and my phone won't be able to "see" satellites below in cabin...?

Sometimes phones can actually see the satellites, if not all the way forward, maybe in some intermediate space where you'd be able to hear the alarm.

Or... sometimes tablets can get better reception. (Or it might be a fluke, but I've seen that happen a couple times, anyway).

Or... I've read that some folks use a baby monitor system, transmitter on the bridge, receiver in the master berth... to act as a repeater for bridge instrumentation. In the grand scheme of things, and if you've got enough battery to run your whole electronics suite overnight at anchor, this one could also get you depth alarms, geo-fencing, etc., depending on whatever you've got installed.

-Chris

 

[ranger58sb]

Convex flukes (plow) tends to shed the substrate where it is lost, not retained on the fluke and lost to the benefit of holding power.

The convex fluke sheds the substrate a bit like rain on a roof. The substrate readily tends to sluff off the fluke, to the side of the anchor doing little to hold it down.

As I understand it...

Rex disputes all that, at least for his anchors. He also argues his anchors with convex flutes are not plows.

Except he spells it ploughs.

-Chris

 

[ranger58sb]

Must be plenty of other members w the Delta.
Any input may need a new thread though.

We used a Delta in the past. The first was an earlier Simpson-Lawerence version, with weighted toe. (Not sure the current Lewmar version includes the toe weight.) Ours was one step oversize for the boat. Worked OK, mostly... except when it didn't.

When it didn't, at least in our case, it has been all about soft mud...

Although the very first time, we had us and about eight 35'+ sailboats on the raft using our Delta... the bottom really was slimy... and the tide started coming in... so in that case, it wasn't really the anchor's fault.

I think it's an elegant design: one moving part. The second one always worked well when we lived down in FL. But... the shape and size of the flukes doesn't make it stand out in the soft mud we have around here on the Chesapeake...

-Chris

 

[foggysail]

If there are Delta lovers out there....well, my 50# is gone along with the Bruce 44 but I still have an 88# Delta with the original luster. Yes, it is as heavy as 88# can be but I will help to put it into your vehicle. BIG DISCOUNT. Hard to say goodbye to an old friend.

 

[Nomad Willy]

As I understand it...

Rex disputes all that, at least for his anchors. He also argues his anchors with convex flutes are not plows.

Except he spells it ploughs.

-Chris

Chris I know about how Rex feels about the name "plough" but as far as I know that's what they call the anchors w convex flukes like the CQR, Delta, Davis that looks like a Delta, ect.
I think the SARCA is not really realted to plow anchors beyond the convex fluke. And part of the reason Rex dos'nt like the name is because often the SARCA is described as being "agricultural" in general appearence.
I could stop calling them plow anchors but what would I call them? I'll just call them SARCA's here to be nice. Perhaps that would help. The Excel is harder to take out of the plow category. But again I can avoid the word. It would be great if I was wrong and they have another name. I'll read some old anchor tests and see.